When the mains supply is turned onto the ATX power supply, it switches +5V standby on and then we press the reset button on the front panel to switch on the ATX power supply. if i shutdown the windows and then switch the mains supply off to ATX power supply, it losses the +5V standby supply after a minute. If i then swiitch off the mains power, the processor and the lcd panel comes on momentariliy for a second and then switches off waiting for the reset button to be pressed to turn the system on. However, if i turn the mains supply off and on during the 1 minute period whilst the +5V standby is on, the processor and lcd does not come on momentarily. Any ideas please.

The processor is Intel atom ETX DC 1.66 GHz N455 and used on a mother board for a user interface PC.

There is 350 ms delay on ATX PS On signal (Pin 14 Active low) compared to +5V standby voltage when the mains supply is turned on . As a result, during this 350 ms delay the processor and the lcd display comes on momentarily as the power supply is turned on until the PSU on signal goes logic high to turn off the power supply.

The PS On signal is a direct output from the ETX module to ATX power supply..

As long as the windows is shutdown and mains supply is left on, it is not an issue as the Ps On signal is at logic high when the PC is turned on via the reset button on the front panel.

Based on that information, I can see here that the manufacturer of the board is: Kontron, and since the power supply is directly related to the board, one of the things we can try is to check directly with them, in order to find out if the board is working properly: